Patrick de Man, owner of Fitworld gym in the town of Heteren, said he got the idea in part from two of his customers who are avid nudists.

"I heard that some other gyms are offering courses on 'pole-dancing' as a sport, so I thought: Why not bring something new to the market?" de Man said.

He said the response had been overwhelming — positive and negative.

The 70,000-member Dutch Federation of Naturists was curious to see if Fitworld's plan would work, spokesman Bernd Huiser said. 

"We recently conducted a large survey among our members, and most prefer to exercise with their clothes on," he said. "The most popular activities (for nudists) are things you do outdoors, like walking on the beach, or swimming in a lake, or maybe gardening."

De Man said the first question Fitworld customers were asking was whether it would be sanitary.

Nude exercisers would be required to put towels down on weight machines and to use disposable seat covers while riding bikes. All machines would be cleaned and disinfected afterward. "We clean them every day anyway," he said.

The first "Naked Sunday" is scheduled for March 4.